Multipurpose controller for multistate windows

ABSTRACT

“Smart” controllers for windows having controllable optical transitions are described. Controllers with multiple features can sense and adapt to local environmental conditions. Controllers described herein can be integrated with a building management system (BMS) to greatly enhance the BMS&#39;s effectiveness at managing local environments in a building. The controllers may have one, two, three or more functions such as powering a smart window, determining the percent transmittance, size, and/or temperature of a smart window, providing wireless communication between the controller and a separate communication node, etc.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/049,756, by Brown et al., entitled “Multipurpose Controller forMultistate Windows” and filed on Mar. 16, 2011, which application isincorporated herein by reference in its entirety and for all purposes.U.S. patent application Ser. No. 13/049,756 is related to U.S. patentapplication Ser. No. 13/049,623, by Pradhan et al., entitled“Controlling Transitions In Optically Switchable Devices” and filed Mar.16, 2011 (now U.S. Pat. No. 8,254,013, issued Aug. 28, 2012), and U.S.patent application Ser. No. 13/049,750, by Shrivastava et al., entitled“Onboard Controller for Multistate Windows” and filed Mar. 16, 2011 (nowU.S. Pat. No. 8,213,074, issued Jul. 3, 2012), which applications areincorporated herein by reference in their entirety and for all purposes.

FIELD

The invention relates generally to electrochromic devices, moreparticularly to controllers for electrochromic windows.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits areversible electrochemically-mediated change in an optical property whenplaced in a different electronic state, typically by being subjected toa voltage change. The optical property is typically one or more ofcolor, transmittance, absorbance, and reflectance. One well knownelectrochromic material is tungsten oxide (WO₃). Tungsten oxide is acathodic electrochromic material in which a coloration transition,transparent to blue, occurs by electrochemical reduction.

Electrochromic materials may be incorporated into, for example, windowsfor home, commercial and other uses. The color, transmittance,absorbance, and/or reflectance of such windows may be changed byinducing a change in the electrochromic material, that is,electrochromic windows are windows that can be darkened or lightenedelectronically. A small voltage applied to an electrochromic device (EC)of the window will cause them to darken; reversing the voltage causesthem to lighten. This capability allows control of the amount of lightthat passes through the windows, and presents an opportunity forelectrochromic windows to be used as energy-saving devices.

While electrochromism was discovered in the 1960's, EC devices, andparticularly EC windows, still unfortunately suffer various problems andhave not begun to realize their full commercial potential despite manyrecent advancements in EC technology, apparatus and related methods ofmaking and/or using EC devices.

SUMMARY OF INVENTION

“Smart” controllers for EC windows are described. Controllers withmultiple features can sense and adapt to local environmental conditions.Controllers described herein can be integrated with a buildingmanagement system (BMS) to greatly enhance the BMS's effectiveness atmanaging local environments in a building. Controllers described hereinmay have functionality for providing one, two, three or more of thefollowing features: (a) powering an EC device of an EC window; (b)determining percent transmittance of an EC window; (c) determining sizeof an EC window; (d) determining temperature of an EC device of an ECwindow; (e) determining damage to an EC device of an EC window; (f)determining wire length between the EC window controller and an ECwindow; (g) wireless communication between the EC window controller anda separate communication node; (h) storing and transmitting datarelating to an EC window via an RFID tag that is actively or passivelypowered; (i) storing charge resulting from a transition of an EC deviceof the EC window and/or direct such charge to a power grid; (j)repairing short related defects of an EC device of an EC window; and (k)heating one or both electrodes of an EC device of an EC window.

In one disclosed aspect, a window controller for controlling one or morewindows capable of undergoing reversible optical transitions isconfigured or designed to provide at least two functions. In certainembodiments may be any two of the following: (a) powering a reversibleoptical transition of at least one of the one or more windows; (b)determining transmittance of at least one of the one or more windows;(c) determining a size of at least one of the one or more windows; (d)determining temperature of at least one of the one or more windows; (e)determining damage to at least one of the one or more windows; (f)determining wire length between the window controller and at least oneof the one or more windows; (g) wireless communication between thewindow controller and a separate communication node; (h) storing andtransmitting data relating to at least one of the one or more windowsvia an RFID tag that is actively or passively powered; (i) storingcharge resulting from a transition of at least one of the one or morewindows and/or direct such charge to a power grid; (j) repairing shortrelated defects of at least one of the one or more windows; and (k)heating one or both electrodes of an electrochromic device of at leastone of the one or more windows. In various embodiments, the controlleris configured or designed to provide at least functions (b), (c), (d)and (e). In other embodiments, the controller is configured or designedto provide at least functions (a), (b), (c), (d) and (e). In still otherembodiments, the controller is configured or designed to provide atleast functions (a), (b), (d), (g), and (h).

Some disclosed aspects concern a controller as described but provided aspart of a larger combination of system of elements such as a buildingmanagement system containing window controller as described. In anotherexample, an apparatus includes (i) a Building Management System (BMS);(ii) the window controller as described above; and (iii) a multistateelectrochromic window. In yet another example, an apparatus includes (i)the window controller as described above, and (ii) an electrochromicwindow. In various embodiments, the electrochromic window is entirelysolid state and inorganic.

Other disclosed aspects pertain to methods of managing a building'ssystems. Such methods may make use of data collected by a windowcontroller from one or more windows capable of undergoing reversibleoptical transitions in the building. This data is used as input foradjusting at least one other system of the building, such as HVAC,lighting, security, power, fire suppression and elevator control. Insome related methods, the controller provides power to the one or morewindows to drive the reversible optical transitions. In a specificembodiment, the method includes the following operations: (a) poweringthe reversible optical transition of at least one of the one or morewindows; (b) determining transmittance of at least one of the one ormore windows; (c) determining temperature of at least one of the one ormore windows; (d) wireless communication between the window controllerand a separate communication node; and (e) storing and transmitting datarelating to at least one of the one or more windows via an RFID tag thatis actively or passively powered.

In a specific example, the method further involves collecting one ormore of the following types of data about the one or more windows:transmittance, size, temperature. In a different example, the methodadditionally involves storing data, in the controller, about the one ormore windows.

Still other disclosed aspects pertain to window controllers forcontrolling one or more windows capable of undergoing reversible opticaltransitions, where the window controllers are configured or designed toprovide the following functions: (a) powering a reversible opticaltransition of at least one of the one or more windows; (b) determiningtransmittance of at least one of the one or more windows; (c)determining temperature of at least one of the one or more windows; (d)communication between the window controller and a separate communicationnode; and (e) storing and transmitting data relating to at least one ofthe one or more windows.

In such controllers, the function of determining temperature of at leastone of the one or more windows may be implemented by direct measurementfrom one or more sensors on the at least one window. Alternatively, thefunction of determining temperature of at least one of the one or morewindows may be implemented by algorithmically inferring temperature fromcurrent and/or voltage information from the at least one window.

In such controllers, the function of powering the reversible opticaltransition may be implemented with pulse width amplifier rendered as anh-bridge or a buck converter. Additionally or alternatively, thefunction of determining transmittance of at least one of the one or morewindows is implemented by direct measurement from one or more sensors onthe at least one window. In certain embodiments, the function of storingand transmitting data relating to at least one of the one or morewindows may involve reading data from a controller embedded in the atleast one window.

These and other features and advantages will be described in furtherdetail below, with reference to the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description can be more fully understood whenconsidered in conjunction with the drawings in which:

FIG. 1 depicts a an EC window controller interfaced with a buildingmanagement system.

FIG. 2 is a schematic representation of a charge storage mechanism ofcontrollers described herein.

FIG. 3 is a schematic of an onboard window controller.

FIG. 4 depicts a different onboard window controller and associated userinterface.

FIG. 5 is a cross section schematic of an all solid state and inorganicEC device on a substrate.

DETAILED DESCRIPTION

Conventional EC window controllers have a number of pitfalls. Forexample, they typically need to be calibrated at the factory for aspecific insulated glass unit (IGU) size and wire length—any mismatch atthe time of installation can cause problems. Also, conventional windowcontrollers must be hard wired to a building management system andcommands to the controller are usually entered by hand at the controlleror via a BMS. Sensors on such window controllers typically have separatesensors for providing data feedback for control of the window and forsupplying a BMS with data. Conventional EC window controllers also arelimited in the type of data they collect from the EC window environmentand how they collect such data. Controllers described herein do notsuffer from such issues. Multipurpose EC window controllers describedherein include features that provide easier installation, improved userinterfaces, wireless communication and control, higher and consistentperformance under varying conditions and capability to enhanceenvironmental conditions, for example, when integrated into a buildingmanagement system.

EC Devices

Controllers described herein are used to control EC devices,particularly in EC windows. Virtually any EC device will work withmultipurpose controllers described herein. Additionally,non-electrochromic optically switchable devices such liquid crystaldevices and suspended particle devices. For context, EC devicetechnology is described below in relation to all solid state andinorganic EC devices, particularly low-defectivity all solid state andinorganic EC devices. See the discussion associated with FIG. 5. Becauseof their low defectivity and robust nature, these devices areparticularly well suited for multipurpose controllers described herein.One embodiment is any controller described herein where the controllerincludes one or more EC devices selected from those described herein.

EC Windows

Electrochromic windows may use one or more EC devices and for those thatuse more than one EC device, more than one type of EC device can used ina window unit (IGU plus frame and/or accompanying structural support).An EC window will typically have wires or leads that extend from the busbars of the EC device(s) through a seal in the IGU. These leads may alsopass through a window frame. A window controller is wired to the leads,for example, near the EC window or not. EC windows are described in thepatent applications incorporated by reference herein. Although notlimited to such use, multipurpose controllers described herein findparticular use with multistate EC windows, that is, windows that cantransition not only between disparate states of coloring and bleaching,but also can transition to one or more intermediate colored states.Particular examples of multistate windows, having two or more EC panes,are described in U.S. patent application Ser. No. 12/851,514, filed onAug. 5, 2010, and entitled “Multipane Electrochromic Windows,” which isincorporated by reference herein for all purposes. One advantage to suchmultipane EC windows is that the likelihood of defects in each of the ECpanes aligning perfectly, and thus being observable to the end user, isquite small. This advantage is accentuated when low-defectivity panesare used. Controllers described herein are well suited for controllingand coordinating the function of one or more EC devices, for example, ina single window.

When used in combination with EC windows that have superior performancecharacteristics, for example short transition times, low-defectivity,long life, uniform transitions and the like, for example, all solidstate and inorganic EC windows, the window controllers described hereinsignificantly augment environmental control in a building. This isparticularly true when window controllers are integrated with a BMS.Interrelationships between window performance, microclimate sensing, andenvironmental control are described in more detail below.

Building Management Systems

Although not limited to this context, multipurpose controllers describedherein are well suited for integration with a BMS. A BMS is a computerbased control system installed in a building that monitors and controlsthe building's mechanical and electrical equipment such as ventilation,lighting, power systems, elevators, fire systems, and security systemsincluding automatic door locks, alarms, turnstiles and the like. A BMSconsists of hardware and associated software for maintaining conditionsin the building according to preferences set by the occupants and orbuilding manager. The software can be based on, for example, internetprotocols and/or open standards.

A BMS is most common in a large building, and typically functions atleast to control the environment within the building. For example, a BMSmay control temperature, carbon dioxide levels and humidity within abuilding. Typically there are many mechanical devices that arecontrolled by a BMS such as heaters, air conditioners, blowers, vents,and the like. To control the building environment, a BMS may turn on andoff these various devices under defined conditions. A core function of atypical modern BMS is to maintain a comfortable environment for thebuilding's occupants while minimizing heating and cooling losses. Thus amodern BMS is used not only to monitor and control, but also to optimizethe synergy between various systems, for example to conserve energy andlower building operation costs. One embodiment is a multipurposecontroller as described herein, integrated with a BMS, where themultipurpose controller is configured to control one or more EC windows.In one embodiment, the one or more EC windows include at least one allsolid state and inorganic EC device. In one embodiment, the one or moreEC windows include only all solid state and inorganic windows. In oneembodiment, the EC windows are multistate EC windows as described inU.S. patent application Ser. No. 12/851,514, filed on Aug. 5, 2010, andentitled “Multipane Electrochromic Windows.”

FIG. 1 is a schematic of a BMS, 100, that manages a number of systems ofa building, 101, including security systems, heating/ventilation/airconditioning (HVAC), lighting of the building, power systems, elevators,fire systems and the like. Security systems may include magnetic cardaccess, turnstiles, solenoid driven door locks, surveillance cameras,burglar alarms, metal detectors and the like. Fire systems may includefire alarms, fire suppression systems including water plumbing control.Lighting systems may include interior lighting, exterior lighting,emergency warning lights, emergency exit signs, and emergency flooregress lighting. Power systems may include main power, backup powergenerators, and uninterrupted power source (UPS) grids.

Also, BMS 100 manages a window controller, 102. In this example, windowcontroller 102 is depicted as a distributed network of windowcontrollers including a master controller, 103, intermediatecontrollers, 105, and end or leaf controllers, 110. For example, mastercontroller 103 may be in proximity to the BMS, and each floor ofbuilding 101 may have one or more intermediate controllers 105, whileeach window of the building has its own end controller 110. In thisexample, each of controllers 110 controls a specific EC window ofbuilding 101.

Each of controllers 110 can be in a separate location from the EC windowthat it controls, or be integrated into the EC window. For simplicity,only ten EC windows of building 101 are depicted as controlled by windowcontroller 102. In a typical setting there may be a very large number ofEC windows in a building controlled by window controller 102. Windowcontroller 102 need not be a distributed network of window controllers,for example, a single end controller which controls the functions of asingle EC window also falls within the scope of the invention.Advantages and features of incorporating multipurpose EC windowcontrollers as described herein with BMS's are described below in moredetail and in relation to FIG. 1 where appropriate.

One aspect of the invention is a BMS including a multipurpose EC windowcontroller as described herein. By incorporating feedback from amultipurpose EC window controller, a BMS can provide, for example,enhanced: 1) environmental control, 2) energy savings, 3) security, 4)flexibility in control options, 5) improved reliability and usable lifeof other systems due to less reliance thereon and therefore lessmaintenance thereof, 6) information availability and diagnostics, 7)effective use of staff, and various combinations of these, because theEC windows can be automatically controlled. Such multipurposecontrollers are described in more detail below, for example, in thecontext of being integrated into a BMS, however, the invention is notlimited in this way. Multipurpose controllers of the invention may bestand alone controllers, for example, configured to control thefunctions of a single window or a plurality of EC windows, withoutintegration into a BMS.

Multipurpose Controllers for EC Windows

Window controllers described herein have a microprocessor that controlsone or more functions of one or more EC devices of an EC window. In oneexample, the controller regulates the potential applied to the EC deviceof the window and may optionally control other functions (alone orcombined with other microprocessors) such as recharging a battery usedto function the window, wirelessly communicating with a remote control,such as a hand held (“clicker”) and/or a BMS.

Because electrochromic windows offer enhanced control of not only theamount of light that enters the interior of a building, but also canserve, for example, to keep heat in, or out, of a building by providinga superior thermal barrier, the benefits of EC windows are enhanced bymultipurpose controllers described herein. This is especially true whenthe controllers are integrated with a BMS, for example, in a buildinghaving many EC windows. The benefits are multiplied even more when themultipurpose controllers are not only integrated into a BMS, but alsoare used to control the functions of multistate EC windows.

In one embodiment, the EC window controller is a multipurposecontroller, that is, it can control and/or monitor a number of functionsand/or characteristics of one or more EC windows. One way to enhance thecapabilities of a BMS which includes an EC window controller into itssystems is to have a window controller with such enhanced capabilitiesproviding feedback to the BMS, particularly where the feedback includesa number of parameters and on a more granular, window-by-window basis.These capabilities and/or functions allow synergistic control of, forexample, a building's energy requirements and thus can save money aboveand beyond installing EC windows in a building, with or withoutconventional automatic control of the windows. The more efficient andversatile the EC windows employed in such a system, the greater energysavings and environmental control. Multistate EC windows are anexemplary choice for BMS's configured with multipurpose controllers.

Embodiments described herein include multipurpose controllers that cancontrol one or more EC devices of an EC window and also one or morefunctions of each EC device of the associated window. One aspect of theinvention is an EC window controller that includes one, two, three ormore of the following functions: (a) powering an EC device of the ECwindow; (b) determining percent transmittance of an EC window; (c)determining size of the EC window; (d) determining temperature of an ECdevice of the EC window; (e) determining damage to an EC device of theEC window; (f) determining wire length between the EC window controllerand the EC window; (g) wireless communication between the EC windowcontroller and a separate communication node; (h) storing andtransmitting data relating to an EC window via an RFID tag that isactively or passively powered; (i) storing charge resulting from atransition of an EC device of the EC window and/or direct such charge toa power grid; (j) repairing short related defects of an EC device of theEC window; and (k) heating one or both electrodes of an EC device of theEC window. Each of these capabilities and functions is described in moredetail below.

Powering an EC Device

In some embodiments, the multipurpose controller can power one or moreEC devices in an EC window. Typically, this function of the controlleris augmented with one or more other functions described in more detailbelow. Controllers described herein are not limited to those that havethe function of powering an EC device to which it is associated for thepurposes of control. That is, the power source for the EC window may beseparate from the controller, where the controller has its own powersource and directs application of power from the window power source tothe window. However, it is convenient to include a power source to thecontroller and configure the controller to power the window directly,because it obviates the need for separate wiring for powering the ECwindow.

One embodiment is a window controller with one, two, three or morecapabilities described herein, where at least one of the capabilities isto control the optical state of an EC window. In various embodiments,there are certain conditions in which current and voltage may to beindividually limited, and there is an optimum sequence by which thewindow is controlled with current limits and/or voltage limits to ensurereasonably quick and non-damaging optical transitions (such as coloringand bleaching an electrochromic window). Examples of such sequences aredisclosed in U.S. patent application Ser. No. 13/049,623, namingPradhan, Mehtani, and Jack as inventors, titled “Controlling TransitionsIn Optically Switchable Devices” and filed on Mar. 16, 2011, which isincorporated herein by reference in its entirety. As part of the windowcontrol process, the controller may receive measurements of currentand/or voltage on a window. Once such measurements are made the“control” function may impose appropriate current and/or voltage limitsto allow the window to reliability change state.

An example of powering an electrochromic window involves use of acontroller having a pulse width modulated amplifier (see FIG. 3)rendered as an “h-bridge” which allows the load to float, be grounded,or be set to any voltage or polarity between the input voltage to thecontroller and ground. In other embodiments, an EC controller isimplemented using a “buck converter” and a separate polarity switchallowing the load to set to any voltage or polarity between the inputvoltage to the controller and ground. Control may also include currentlimits during all or part of the transition from one state to another.

Percent Transmittance (% T)

Electrochromic windows have at least one EC device deposited on a glassor other transparent substrate and may have other coatings and panesthat are part of an IGU in a window unit. The percent transmittance (%T) of an EC window, typically the integrated transmittance across thevisible spectrum for an IGU of an EC window, is an important parameterbecause it is a measure of how much light is entering a room where thewindow is installed. When using windows with multistate capability, thatis having intermediate states as well as end states of colored andbleached, it may be important to have feedback on the % T in order tomaintain a particular state of transition and/or move to a new colortransition according to the desire of the end user. Controllersdescribed herein can measure % T by use of sensors and/or by usingcurrent/voltage (I/V) parameters to calculate % T.

Determining the % T can be inferred algorithmically or measured directlyusing a sensor (e.g. a photometric sensor such as a silicon photodiode)wired to a controller's analog input (AI-Transmittance). See FIGS. 3 and4, discussed below. Another acceptable sensor is a pyranometer whichmeasures solar irradiance across a larger spectrum of solar radiation.

In one embodiment, the controller includes a sensor on the outside ofthe building (or window side which will face outside when installed),which serves one or more EC windows and measures the solar spectrum thatis entering the window or windows, and one more internal sensors whichmeasure solar irradiance transmitted through the window of each window'sIGU. These two energy values are compared in logic in the controller toprovide a measure of % T of the window. When one sensor on the outsideof the building (or window) is used to serve more than one window, thecontroller will typically sample solar irradiance on the exterior foruse in calculating (effective) % T of each window unit. Sensors arecalibrated to their respective IGU's, for example, when installed orreplaced in the field.

In one embodiment, the controller employs an outside and an insidesensor for % T for each window. This embodiment is particularly wellsuited for obtaining more granular feedback on % T for adjustingindividual windows' transmissivities accordingly, or for example whenthe window controller is integrated into a BMS, for adjusting a numberof parameters of a building such as HVAC and the like. For example,referring again to FIG. 1, window controller 102 controls five ECwindows on side A of building 101, and five windows on side B ofbuilding 101. These windows are depicted as being on the top floor ofbuilding 101. In this example, intermediate controller 105 a controlsthree windows of one room of building 101, and intermediate controller105 b controls seven windows in another room, two on side A of building101 and five on side B of building 101. In this example, there is ashadow of a cloud on side B of building 101 because a cloud is obscuringpart of the sun's rays. Assuming all the EC windows are of the same sizeand type, each of the two windows controlled by intermediate controller105 b on side A of building 101 will have the same approximate % T,while each of the five windows controlled by intermediate controller 105b on side B of building 101 will have different % T values because eachhas a different percent area covered by the shadow from the cloud.

This granularity in data feedback is highly valuable in controlling theenvironment, for example light, heat, etc., in the room having theseseven windows. Intermediate controller 105 b uses the % T feedback tomaintain the desired environment in the room having these seven windows.Master controller 103 uses the data from intermediate controller 105 aand 105 b to control the environment of both rooms. For example if theroom having the EC windows controlled by intermediate controller 105 bis a conference room with many people, the drop in % T due to thecloud's shadow will make the room easier to cool, or for example, lessenthe power requirements for darkening the window during a slidepresentation in the conference room.

Multipurpose controllers described herein include logic for using thistype of feedback for adjusting parameters of the building, via a BMS,for maximizing energy savings. In this example, the energy saved in theconference room due to the shadow's cooling and darkening effects can beused for transitioning windows in the room controlled by intermediatewindow controller 105 a, or, for example, the energy can be stored forlater use in the windows in the conference room (see “Charge Storage”below).

In one embodiment, % T is inferred from the I/V characteristics of an ECdevice of the IGU. An IGU or a window can be characterized by therelationship between an electrical pulse sent through the device and howthe device behaves before and after the pulse. For example, a directcurrent (DC) pulse is sent through an EC device of an IGU, and the DCvoltage measured across the electrodes (TCO's) of the device as a resultprovides an I/V characteristic of the device. Environmental factors suchas temperature or material characteristics of the device can producenon-linear I/V relationships (and cause hysteresis). Thus EC devices aretested at varying temperatures in order to create data for programminginto the logic of controllers of the invention for reference whendetermining various characteristics of the IGU installed with thecontroller. In one embodiment, % T is measured in this way. For example,upon power up, the controller sends a pre-determined signal to the IGUof a window and based on the IGU's response to the signal, the % T iscalculated by knowing the hysteresis curve of the EC device of the IGU.% T may also be inferred as a function of “ionic current,” which can becalculated by measuring the applied current and subtracting the leakagecurrent.

In one embodiment, the open circuit voltage (V_(oc)) of the EC device ismeasured, then an electrical pulse is applied, followed by measuring theV_(oc) again. The change in the V_(oc) as a result of the electricalpulse allows calculation of % T based on, for example, priorcharacterization of the device. In one example, the temperature of thedevice is measured along with V_(oc) and the % T calculated based on theEC device's behavior to such pulses in previous characterization tests.

Size and Temperature of the IGU

The temperature of an electrochromic device can be inferredalgorithmically or measured directly using a sensor (e.g. athermocouple, thermister, or RTD (resistive thermal device)). In variousembodiments, such device is wired or otherwise communicatively coupledto a controller analog input (AI-EC Temperature). See FIGS. 3 and 4.

Using I/V measurements as described above, along with characterizationdata of the IGU, the size and temperature of the IGU can be determinedby controllers described herein. For example, for each of a 20″ by 20″window, a 40″ by 40″ window and a 60″ by 60″ window, data is collectedbased on UV measurements at a number of temperatures. This data isprogrammed into a window controller which has distinct capabilities andfunctions with respect to these three window sizes. In the field, duringinstallation, an installer connects the window controller so programmedwith an EC window. The controller sends an electrical pulse through theIGU of the window and from the current response, and correlating withthe programmed data, the controller can determine the size andtemperature of the window. This information is used, for example, toprogram the controller's logic according to the appropriate window sizeso that, for example, the appropriate power is used to transition thewindow during operation.

Damage to the EC Device

In one embodiment, window controllers described herein use I/Vcharacteristics such as those described above to determine damage to anEC device in an IGU of an EC. For example, given the characterizedleakage current of the EC device programmed into the controller's logic,when the controller pings the IGU for I/V feedback, this data can becompared to the data for that IGU from the factory and/or wheninstalled. If the leakage current is greater than it was atinstallation, then damage to the IGU is likely. The larger the change inI/V characteristics, the more likely damage has occurred to the ECdevice of the IGU. For example, if the window is damaged by an objecthitting the window, controllers described herein would detect the damage(for example a large electrical short) as described and, for example,alert the appropriate repair or security personnel via a BMS. In anotherexample, over time, a number of defects arise in the EC device of an IGUwhich results in a change in I/V characteristics of the window. Thisdata is fed back to an end user and/or a BMS to inform the appropriatepersonnel that the IGU needs to be replaced or repaired (see “In FieldShort-Related Defect Repair” below).

Wire Length: Ranging

Controllers described herein may have the logic and associated hardwareto determine the length of wire between a window and the controller. Forexample, the controller may apply an electrical signal to the wiringthat leads to the one or more IGU's that they control and then measurethe change in frequency in the line transmission of the signal. Thischange in frequency is used to determine the length of the wiring or“range” between the controller and the IGU. Knowing the length of thewiring can be important because the amount of power provided by thesource is dependent on how much wiring the power must traverse, as thereis a power drop off associated with resistance in the wire. The powersource may need to adjust the amount of power it sends to power windowsseparated from it by differing lengths of wire.

Ranging is typically done between an end controller and an associatedIGU in a window. Ranging can be done either actively or passively. Inactive ranging, the EC device of the IGU is active and can reply to asignal from the controller. In passive ranging, the EC device isswitched out of the circuit while ranging is performed.

In certain implementations, a relay is provided at the IGU end of thewire, typically embedded in the IGU secondary seal. The controller sendsa message down IGU power lines (using, e.g., MAXIM's OneWire interface,see www.maximic.com/products/1-wire/flash/overview/index.cfm(incorporated by reference)), and the IGU then switches itself out ofthe circuit for a finite time period to allow the controller to conducta ranging test. At some predefined time interval the IGU would thenswitch itself back into the circuit and allow normal control of the IGUto resume.

In some embodiments, the controller is located in or very near thewindow frame, and thus ranging is not necessary as all end controllershave the same length of wiring between them and their respective IGU's.

Wireless or Wired Communication

In some embodiments, window controllers described herein includecomponents for wired or wireless communication between the windowcontroller and separate communication node. Wireless or wiredcommunications may be accomplished with a communication interface thatinterfaces directly with the window controller. Such interface could benative to the microprocessor or provided via additional circuitryenabling these functions.

A separate communication node for wireless communications can be, forexample, another wireless window controller, an end, intermediate ormaster window controller, a remote control device, or a BMS. Wirelesscommunication is used in the window controller for at least one of thefollowing operations: programming and/or operating the EC window,collecting data from the EC window from the various sensors andprotocols described herein, and using the EC window as a relay point forwireless communication. Data collected from EC windows also may includecount data such as number of times an EC device has been activated,efficiency of the EC device over time, and the like. Each of thesewireless communication features is described in more detail below.

In one embodiment, wireless communication is used to operate theassociated EC windows, for example, via an infrared (IR), and/or radiofrequency (Rf) signal. In certain embodiments, the controller willinclude a wireless protocol chip, such as Bluetooth, EnOcean, WiFi,Zigbee, and the like. Window controllers may also have wirelesscommunication via a network. Input to the window controller can bemanually input by a user, either directly or via wireless communication,or the input can be from a BMS of a building of which the EC window is acomponent.

In one embodiment, when the window controller is part of a distributednetwork of controllers, wireless communication is used to transfer datato and from each of a plurality of EC windows via the distributednetwork of controllers, each having wireless communication components.For example, referring again to FIG. 1, master window controller 103,communicates wirelessly with each of intermediate controllers 105, whichin turn communicate wirelessly with end controllers 110, each associatedwith an EC window. Master controller 103 may also communicate wirelesslywith the BMS. In one embodiment, at least one level of communication inthe window controller is performed wirelessly.

In some embodiments, more than one mode of wireless communication isused in the window controller distributed network. For example, a masterwindow controller may communicate wirelessly to intermediate controllersvia WiFi or Zigbee, while the intermediate controllers communicate withend controllers via Bluetooth, Zigbee, EnOcean or other protocol. Inanother example, window controllers have redundant wirelesscommunication systems for flexibility in end user choices for wirelesscommunication.

Wireless communication between, for example, master and/or intermediatewindow controllers and end window controllers offers the advantage ofobviating the installation of hard communication lines. This is alsotrue for wireless communication between window controllers and BMS. Inone aspect, wireless communication in these roles is useful for datatransfer to and from EC windows for operating the window and providingdata to, for example, a BMS for optimizing the environment and energysavings in a building. Window location data as well as feedback fromsensors are synergized for such optimization. For example, granularlevel (window-by-window) microclimate information is fed to a BMS inorder to optimize the building's various environments.

A BMS may also collect data on how many times an EC device is poweredand the like for higher level feedback to vendors, for example, onquality control and reliability of the windows installed in thebuilding. However, there are other advantages for such wirelesscommunications. For example, since EC window control and data transferdoes not require a large amount of bandwidth, having a distributednetwork of wirelessly linked windows and controllers offers a veryuseful opportunity to use the network for other purposes. In oneembodiment, the wireless window controller network is used for relayingother, non-EC window related information within a building. Zigbee, forexample, uses the window controller to build a mesh network, with otherwindow controllers or other devices like dimmable ballasts, alarmsystems, etc. that also employ Zigbee. As such network traffic passingthrough the window controller may not be related to window control atall, the window controller is simply improving the mesh reliability.

Radio Frequency Identification

Radio-frequency identification (RFID) involves interrogators (orreaders), and tags (or labels). RFID tags use communication viaelectromagnetic waves (typically radio frequency) to exchange databetween a terminal and an object, for example, for the purpose ofidentification and tracking of the object. Some RFID tags can be readfrom several meters away and beyond the line of sight of the reader.

Most RFID tags contain at least two parts. One is an integrated circuitfor storing and processing information, modulating and demodulating aradio-frequency (Rf) signal, and other specialized functions. The otheris an antenna for receiving and transmitting the signal.

There are three types of conventional RFID tags: passive RFID tags,which have no power source and require an external electromagnetic fieldto initiate a signal transmission, active RFID tags, which contain abattery and can transmit signals once a reader has been successfullyidentified, and battery assisted passive (BAP) RFID tags, which requirean external source to wake up but have significant higher forward linkcapability providing greater range. RFID has many applications; forexample, it may be used in enterprise supply chain management to improvethe efficiency of EC device inventory tracking and management.

One embodiment is a window controller as described herein including anRFID tag. In one embodiment, the window controller is an end controllerassociated with a particular IGU. In one embodiment, the RFID tag may beinstalled on the IGU prior to installation of the window controller,that is, after the IGU and window controller are wired together, theRFID tag is considered part of the window controller. The RFID tag maybe active, passive or BAP, depending on the controller's capability topower the RFID. An RFID tag in a window controller as described hereinmay contain at least one of the following types of data: warrantyinformation, installation information, vendor information,batch/inventory information, EC device/IGU characteristics, customerinformation, manufactured date, window size, and specific parameters tobe used for a particular window

Such RFID tags obviate the need for stickers on IGU's or windows withsuch information and some RFID's have rudimentary processing capabilitysuch as keeping track of how many times an associated EC device has beenactivated. An unsophisticated BMS can use such information forenvironmental control, for example, based on known performance of ECdevices as a function of usage. In another example, an installer can usea portable reader to decide which end controller to install in aparticular window and/or the controller itself may read the RFID tag andprogram itself prior to, or upon wiring, to the IGU.

In related embodiments, a controller could also read data from the IGUthat has an embedded (e.g. part of a wiring harness, or encapsulated bythe secondary seal, etc.) but physically separate RFID tag, EEPROM orFLASH memory chip that would allow various details of the window to bestored with one of these storage devices. Examples of information thatmay be stored on the tag or memory device embedded in the IGU includewarranty information, installation information, vendor information,batch/inventory information, EC device/IGU characteristics, an EC devicecycle count, customer information, manufactured date, and window size.

Charge Storage

The amount of ions held in the counter electrode layer during thebleached state (and correspondingly in the EC layer during the coloredstate) and available to drive the EC transition depends on thecomposition of the layers as well as the thickness of the layers and thefabrication method. Both the EC layer and the counter electrode layerare capable of supplying charge (in the form of lithium ions andelectrons) in the neighborhood of several tens of millicoulombs persquare centimeter of layer surface area. The charge capacity of an ECfilm is the amount of charge that can be loaded and unloaded reversiblyper unit area and unit thickness of the film by applying an externalvoltage or potential. In some embodiments, window controllers have thecapability of storing charge that is produced when an associated ECdevice undergoes a transition that produces a charge. In otherembodiments, the charged produced by the EC window transitions isdiverted to a power grid. The charge is then reused, for example, forfurther transitions of EC windows or, for example where a BMS isintegrated with the window controller, for other needs in a buildingwhere appropriate. Although the charge produced by an EC window'sreverse transition is not large, the charge can be stored in, forexample, a battery or sent to a grid where collectively they can bereused, for example, for further window operations includingtransitions.

FIG. 2 depicts a circuit, 200, where an IGU, 205, including an ECdevice, is powered via a source, 210. In accord with embodimentsdescribed herein, source 210 could be part of the window controller, ornot. In this example, when power is supplied to the EC device of IGU205, the EC device transitions to a colored state as depicted in the topportion of FIG. 2. Circuit 200 also includes a charge storage device,215. Device 215 may be a capacitor or battery, for example. As depictedat the bottom of FIG. 2, when the EC device transitions from colored tobleached, upon discontinuing application of power from source 210, thecircuit is reconfigured, for example using double pole switches, to sendthe resultant charge that the EC device creates into charge storagedevice 215. This stored charge may be used to power further transitionsof the EC device in IGU 205, or to power other aspects of the windowcontroller such as electrical pulses for I/V measurements, rangingpulses and the like. In one embodiment, charge from an EC device'stransition is sent to a power grid for combination with other chargefrom other window's transitions for use in the EC window system or forother purposes. By reusing charge created from the transition of ECwindows, the energy efficiency of the windows is enhanced because thischarge is not simply wasted by discharging it to ground.

In Field Short-Related Defect Repair (“AC Zap”)

As discussed above, EC devices can develop short circuit defects betweenoppositely charged conductive layers, for example, when a conductiveparticle makes contact with each of two conductive and electricallycharged layers. When a short circuit occurs, electrons rather than ionsmigrate between the EC layer and the counter electrode, typicallyresulting in bright spots or halos at the location of, and surrounding,the electrical short when the EC device is otherwise in the coloredstate. Over time, some EC windows can develop many such electricalshorts and thus degrade in performance due to a significant increase inthe leakage current and the appearance of many such bright spots. Incertain embodiments, multipurpose window controllers have the capabilityto repair short related defects in associated EC devices. This has thegreat advantage of repairing the IGU rather than replacing it, andrepairing the IGU without removing it from the window unit.

In one embodiment, the window controller repairs short related defectsin the EC device by sending a high voltage alternating current (AC)through the EC device for a period of time. While not wishing to bebound to theory, it is believed that this repairs the short relateddefects because during application of the AC current, the frequency ofthe AC current does not allow ions to move across the EC stackmaterials, but current does flow, especially through the short relateddefects. The device does not transition during the application of ACcurrent and therefore is protected from damage, while the high ACcurrent “overloads” the shorts and burns them out, effectively sealingthe short related defect areas from further current leakage. This methodof in situ repair of short related defects is described in U.S. patentapplication Ser. No. 12/336,455, naming McMeeking et al. as inventors,and filed on May 2, 2008, which is incorporated herein by reference inits entirety.

Window (Resistive) Heating

The electrode layers of EC devices can be used for resistive heating,for example, by passing a current through one of the electrodes and thususing it as a resistive heating element. In one embodiment, the windowcontroller includes the function of heating one or both electrodes of anEC device of the EC window for resistive heating. Resistive heating isuseful for controlling the temperature of IGU for thermal barrier, todefrost the IGU and to control the temperature of the EC device to aidtransitions. In one embodiment, window controllers described herein canalternate between transitioning the device and heating the device to aidin transitions. One embodiment is an apparatus including a multipurposeEC window controller as described herein and an EC window where at leastone transparent conductive oxide layer of an electrochromic device ofthe EC window is configured to be heated independently of operation ofthe EC device.

Examples of Smart Controllers

The above described features of a smart controller may used alone or incombination with one another. A few specific embodiments will now bedescribed. In one embodiment, the following functions are combined in asingle smart controller: (i) powering one or more smart windows, (ii)determining a percent transmittance of the one or more smart windows (atany particular instance in time), (iii) determining the temperature ofthe one or more smart windows (at any particular instance in time), (iv)providing a communications interface for communicating with the one ormore smart windows, and (v) reading data from physically separate memorydevices or tags embedded in IGUs associated with the one or more smartwindows.

In the embodiment just outlined, the powering a smart window may beaccomplished using pulse width modulated amplifier rendered as, forexample, an “h-bridge” allowing the window load to float, be grounded,or be set to any voltage or polarity between the input voltage to thecontroller and ground. The powering function could also be realizedusing a “buck converter” and a separate polarity switch allowing theload to set to any voltage or polarity between the input voltage to thecontroller and ground. Control may also include current limits duringall or part of the transition from one state to another.

Determining the “percent transmittance” can be could be inferredalgorithmically or measured directly using a sensor (e.g. a siliconphoto diode) communicating by a wired or wireless interface to an analoginput (AI-Transmittance) of the controller. See FIGS. 3 and 4, forexample. Determining the “temperature of an electrochromic device” canbe inferred algorithmically or measured directly using a sensor (e.g. athermocouple, thermister, or RTD) communicating by wireless or wiredinterface to an analog input (AI-EC Temperature) of the controller. SeeFIGS. 3 and 4, for example. Wireless and/or wired communications may beaccomplished using a communication interface that interfaces directlywith the smart controller. This may be native to the controller'smicroprocessor or additional circuitry enabling these functions.Finally, the exemplary smart controller may read data from an embeddedmemory devices or tags in the smart windows. Such devices or tags may bepart of a wiring harness, encapsulated by the secondary seal, etc. butphysically separate from the smart controller. Examples of such devicesor tags include RFID tag, EEPROM or FLASH memory chips that would allowall storage of various information about the windows includingtemperature, number of cycles, manufacturing date, etc.

In another embodiment, the following functions are combined in a singlesmart controller: (i) powering one or more smart windows, (ii)determining a percent transmittance of the one or more smart windows (atany particular instance in time), (iii) determining the size of one ormore windows, (iv) measuring the temperature of the one or more smartwindows (at any particular instance in time), (v) determining if damageto the window has occurred (evolved defects), (vi) providing acommunications interface for communicating with the one or more smartwindows, and (vii) reading data from physically separate memory devicesor tags embedded in IGUs associated with the one or more smart windows.

In the embodiment just outlined, the powering a smart window may beaccomplished using pulse width modulated amplifier (either h-bridge orbuck) as outlined in the previous embodiment but now combined withsensors to simultaneously measure current and voltage delivered to theEC window. Transmittance may be determined algorithmically using asingle photo sensor, knowledge of the real-time voltage and currentvalues as the window transitions state and measuring the actual ECwindow temperature with a sensor in direct contact with the EC coating.Furthermore, direct knowledge of the voltage and current profilestogether with measurement of the EC window temperature allowsalgorithmic determination of the window dimensions. The voltage andcurrent sensing capability allows the controller to compare the currentreadings against historic values stored in the controller, or conveyedand retrieved via communication with the BMS, to determine if damage tothe EC coating has occurred.

In yet another embodiment, a controller is designed or configured toperform the following functions: (i) powering a reversible opticaltransition of one or more windows; (ii) determining the transmittance ofthe one or more windows; (iii) determining the temperature of the one ormore windows; and (iv) storing and transmitting data relating to the oneor more windows via an RFID tag or via memory. A separate implementationprovides a controller designed or configured to perform the followingfunctions: (i) powering a reversible optical transition of one or morewindows; (ii) determining the size(s) of the one or more windows; (iii)determining the temperature of the one or more windows; (iv)communicating between the controller and a separate communication node;and (v) storing and transmitting data relating to the one or morewindows via an RFID tag or via memory. Yet another controller isdesigned or configured to perform the following combination offunctions: (i) powering a reversible optical transition of one or morewindows; (ii) determining the transmittance of the one or more windows;(iii) determining the size(s) of the one or more windows; (iv)determining the temperature of the one or more windows; (v) determiningdamage to the one or more windows; (vi) determining a wire lengthbetween the window controller and the one or more windows; (vii)communicating between the window controller and a separate communicationnode; (viii) storing and transmitting data relating to the one or morewindows via an RFID tag or via memory; and (ix) repairing short relateddefects of the one or more windows. In these examples, as well as othersgiven herein, when a controller interfaces with more than one window,the recited functions can apply to any one of the controlled windows, orany combination of these windows, or all of the windows.

Another controller is designed or configured to perform the followingfunctions: (i) powering a reversible optical transition of one or morewindows; (ii) determining temperature of the one or more windows; and(iii) heating a device on the one or more windows. The heated device maybe the electrochromic devices themselves or a separate device formed onthe windows. This embodiment is particularly appropriate for coldweather climates when it is desirable to include relatively largewindows. It permits the windows to operate in a relatively untintedstate when the flux of solar radiation is sufficient. The additionalheating permitted by function (iii) permits use of larger window panesin areas where insulated walls are typically expected in place of largewindows.

Examples of Controller Architectures

FIG. 3 is a schematic depiction of a window controller configuration,300, including an interface for integrating smart windows into, forexample, a residential system or a building management system. Suchcontroller may serve as a smart controller of the type herein describedor it may serve to provide “local” information from a smart windowindirectly controlled by a smart controller. The disclosed embodimentmay be implemented in a controller embedded in an IGU, for example. Suchcontrollers are sometimes referred to as “onboard” controllers and aredescribed in more detail in U.S. patent application Ser. No. 13/049,750,titled “Onboard Controller for Multistate Windows” and filed on Mar. 16,2011, which is incorporated herein by reference in its entirety.

In the depiction of FIG. 3, a voltage regulator accepts power from astandard 24 v AC/DC source. The voltage regulator is used to power amicroprocessor (μP) as well as a pulse width modulated (PWM) amplifierwhich can generate current at high and low output levels, for example,to power an associated smart window. A communications interface allows,for example, wireless communication with the controller'smicroprocessor. In one embodiment, the communication interface is basedon established interface standards, for example, in one embodiment thecontroller's communication interface uses a serial communication buswhich may be the CAN 2.0 physical layer standard introduced by Bosch andwidely used today in automotive and industrial applications. “CAN” is alinear bus topology allowing for 64 nodes (window controllers) pernetwork, with data rates of 10 kbps to 1 Mbps, and distances of up to2500 m. Other hard wired embodiments include MODBUS, LonWorks™, powerover Ethernet, BACnet MS/TP, etc. The bus could also employ wirelesstechnology (e.g. Zigbee, Bluetooth, etc.).

In the depicted embodiment, the controller includes a discreteinput/output (DIO) function, where a number of inputs, digital and/oranalog, are received, for example, tint levels, temperature of ECdevice(s), % transmittance, device temperature (for example from athermistor), light intensity (for example from a LUX sensor) and thelike. Output includes tint levels for the EC device(s). Theconfiguration depicted in FIG. 3 is particularly useful for automatedsystems, for example, where an advanced BMS is used in conjunction withEC windows having EC controllers as described herein. For example, thebus can be used for communication between a BMS gateway and the ECwindow controller communication interface. The BMS gateway alsocommunicates with a BMS server.

Some of the functions of the discrete I/O will now be described.

DI-TINT Level bit 0 and DI-TINT Level bit 1: These two inputs togethermake a binary input (2 bits or 2²=4 combinations; 00, 01, 10 and 11) toallow an external device (switch or relay contacts) to select one of thefour discrete tint states for each EC window pane of an IGU. In otherwords, this embodiment assumes that the EC device on a window pane hasfour separate tint states that can be set. For IGUs containing twowindow panes, each with its own four-state TINT Level, there may be asmany as eight combinations of binary input. See U.S. patent applicationSer. No. 12/851,514, filed on Aug. 5, 2010 and previously incorporatedby reference. In some embodiments, these inputs allow users to overridethe BMS controls (e.g. untint a window for more light even though theBMS wants it tinted to reduce heat gain).

AI-EC Temperature: This analog input allows a sensor (thermocouple,thermister, RTD) to be connected directly to the controller for thepurpose of determining the temperature of the EC coating. Thustemperature can be determined directly without measuring current and/orvoltage at the window. This allows the controller to set the voltage andcurrent parameters of the controller output, as appropriate for thetemperature.

AI-Transmittance: This analog input allows the controller to measurepercent transmittance of the EC coating directly. This is useful for thepurpose of matching multiple windows that might be adjacent to eachother to ensure consistent visual appearance, or it can be used todetermine the actual state of the window when the control algorithmneeds to make a correction or state change. Using this analog input, thetransmittance can be measured directly without inferring transmittanceusing voltage and current feedback.

AI-Temp/Light Intensity: This analog input is connected to an interiorroom or exterior (to the building) light level or temperature sensor.This input may be used to control the desired state of the EC coatingseveral ways including the following: using exterior light levels, tintthe window (e.g. bright outside, tint the window or vice versa); usingand exterior temperature sensor, tint the window (e.g. cold outside dayin Minneapolis, untint the window to induce heat gain into the room orvice versa, warm day in Phoenix, tint the widow to lower heat gain andreduce air conditioning load).

AI-% Tint: This analog input may be used to interface to legacy BMS orother devices using 0-10 volt signaling to tell the window controllerwhat tint level it should take. The controller may choose to attempt tocontinuously tint the window (shades of tint proportionate to the 0-10volt signal, zero volts being fully untinted, 10 volts being fullytinted) or to quantize the signal (0-0.99 volt means untint the window,1-2.99 volts means tint the window 5%, 3-4.99 volts equals 40% tint, andabove 5 volts is fully tinted). When a signal is present on thisinterface it can still be overridden by a command on the serialcommunication bus instructing a different value.

DO-TINT LEVEL bit 0 and bit 1: This digital input is similar to DI-TINTLevel bit 0 and DI-TINT Level bit 1. Above, these are digital outputsindicating which of the four states of tint a window is in, or beingcommanded to. For example if a window were fully tinted and a user walksinto a room and wants them clear, the user could depress one of theswitches mentioned and cause the controller to begin untinting thewindow. Since this transition is not instantaneous these digital outputswill be alternately turned on and off signaling a change in process andthen held at a fixed state when the window reaches its commanded value.

FIG. 4 depicts a controller configuration 402 having a user interface.For example where automation is not required, the EC window controller,for example as depicted in FIG. 3, can be populated without the PWMcomponents and function as I/O controller for an end user where, forexample, a keypad, 404, or other user controlled interface is availableto the end user to control the EC window functions. The EC windowcontroller and optionally I/O controllers can be daisy chained togetherto create networks of EC windows, for automated and non-automated ECwindow applications.

In certain embodiments, the controller 402 does not directly control awindow but may indirectly control one or more windows. The controllermay direct or coordinate the operation of one or more other controllerssuch as controllers 103 and/or 105 in FIG. 1.

Solid-State and Inorganic EC Devices

A description of EC devices is provided for context, because windowcontrollers described herein include functions that use features of ECdevices, for example, in order to measure parameters such astemperature, window size, percent transmission and the like, as well asusing EC devices in a non-conventional sense, for example, using anelectrode of an EC device for resistive heating. Thus structure andfunction of EC devices is described in the context of solid-state andinorganic EC devices, although controllers described herein can controlany EC device. Further, as noted above, such controllers may be usedwith windows having non-electrochromic optically switchable devices suchas liquid crystal devices and suspended particle devices.

FIG. 5 depicts a schematic cross-section of an EC device, 500.Electrochromic device 500 includes a substrate, 502, a conductive layer(CL), 504, an EC layer (EC), 506, an ion conducting layer (IC), 508, acounter electrode layer (CE), 510, and a conductive layer (CL), 514.Layers 504, 506, 508, 510, and 514 are collectively referred to as an ECstack, 520. A voltage source, 516, operable to apply an electricpotential across EC stack 520, effects the transition of the EC devicefrom, for example, a bleached state to a colored state (depicted). Theorder of layers can be reversed with respect to the substrate. The ECdevice 500 may include one or more additional layers (not shown) such asone or more passive layers. Passive layers used to improve certainoptical properties may be included in EC device 500. Passive layers forproviding moisture or scratch resistance may also be included in the ECdevice 500. For example, the conductive layers may be treated withanti-reflective or protective oxide or nitride layers. Other passivelayers may serve to hermetically seal the EC device 500.

Such all solid-state and inorganic EC devices, methods of fabricatingthem, and defectivity criterion are described in more detail in U.S.patent application Ser. No. 12/645,111, entitled, “Fabrication ofLow-Defectivity Electrochromic Devices,” filed on Dec. 22, 2009 andnaming Mark Kozlowski et al. as inventors, and in U.S. patentapplication Ser. No. 12/645,159, entitled, “Electrochromic Devices,”filed on Dec. 22, 2009 and naming Zhongchun Wang et al. as inventors,both of which are incorporated by reference herein for all purposes. Inaccordance with certain embodiments, EC devices where the counterelectrode and EC electrodes are formed immediately adjacent one another,sometimes in direct contact, without separately depositing an ionicallyconducting layer, are used with controllers described herein. Suchdevices, and methods of fabricating them, are described in U.S. patentapplication Ser. Nos. 12/772,055 and 12/772,075, each filed on Apr. 30,2010, and in U.S. patent application Ser. Nos. 12/814,277 and12/814,279, each filed on Jun. 11, 2010—each of the four applications isentitled “Electrochromic Devices,” each names Zhongchun Wang et al. asinventors, and each is incorporated by reference herein in theirentireties. These devices do not have an IC layer per se, but functionas if they do.

It should be understood that the reference to a transition between ableached state and colored state is non-limiting and suggests only oneexample, among many, of an EC transition that may be implemented. Theterm “bleached” refers to an optically neutral state, for example,uncolored, transparent or translucent. Still further, unless specifiedotherwise herein, the “color” of an EC transition is not limited to anyparticular wavelength or range of wavelengths. In the bleached state, apotential is applied to the EC stack 520 such that available ions in thestack that can cause the EC material 506 to be in the colored statereside primarily in the counter electrode 510. When the potential on theEC stack is reversed, the ions are transported across the ion conductinglayer 508 to the EC material 506 and cause the material to enter thecolored state.

In this example, the materials making up EC stack 520 are both inorganicand solid state. Because organic materials tend to degrade over time,inorganic materials offer the advantage of a reliable EC stack that canfunction for extended periods of time. Materials in the solid state alsooffer the advantage of not having containment and leakage issues, asmaterials in the liquid state often do. One embodiment is an apparatusincluding a controller as described herein and an EC device that is allsolid state and inorganic.

Referring again to FIG. 5, voltage source 516 is typically a low voltageelectrical source and may be configured in multipurpose controllers tooperate in conjunction with other components such as sensors, RFID tags,and the like. In certain embodiments, multipurpose controllers describedherein include the capability to supply power to an EC device, forexample, as voltage source 516.

A typical substrate 502 is glass. Suitable glasses include either clearor tinted soda lime glass, including soda lime float glass. Typically,there is a sodium diffusion barrier layer (not shown) between substrate502 and conductive layer 504 to prevent the diffusion of sodium ionsfrom the glass into conductive layer 504.

On top of substrate 502 is conductive layer 504. Conductive layers 504and 514 may be made from a number of different materials, includingconductive oxides, thin metallic coatings, conductive metal nitrides,and composite conductors. Typically, conductive layers 504 and 514 aretransparent at least in the range of wavelengths where electrochromismis exhibited by the EC layer. Transparent conductive oxides includemetal oxides and metal oxides doped with one or more metals. Sinceoxides are often used for these layers, they are sometimes referred toas “transparent conductive oxide” (TCO) layers.

The function of the TCO layers is to spread an electric potentialprovided by voltage source 516 over surfaces of the EC stack 520 tointerior regions of the stack, with very little ohmic potential drop.The electric potential is transferred to the conductive layers thoughelectrical connections to the conductive layers. Typically, bus bars,one in contact with conductive layer 504 and one in contact withconductive layer 514, provide the electric connection between thevoltage source 516 and the conductive layers 504 and 514. Generally,various thicknesses of the layers of the conductive material may beemployed so long as they provide the necessary electrical properties(for example, conductivity) and optical properties (for example,transmittance). Typically, the conductive layers 504 and 514 are as thinas possible to increase transparency and to reduce cost. Preferably, thethickness of the each conductive layer 504 and 514 is also substantiallyuniform.

The sheet resistance (R_(s)) of the conductive layers is also importantbecause of the relatively large area spanned by the layers, for example,when the device is part of an electrochromic window. The sheetresistance of conductive layers 504 and 514 may be between about 5 Ohmsper square to about 30 Ohms per square. In general, it is desirable thatthe sheet resistance of each of the two conductive layers be about thesame. The conductive layers can be exploited for resistive heating ofthe device, by virtue of their sheet resistance, rather than forfunctioning the EC device of which they are a part. In one embodiment,multipurpose controllers described include the function of resistiveheating using one or more conductive layers of an EC device. Suchresistive heating as described in more detail below.

Overlaying conductive layer 504 is EC layer 506. The EC layer maycontain any one or more of a number of different EC materials, includingmetal oxides. An EC layer 506 including a metal oxide is capable ofreceiving ions transferred from counter electrode layer 510. Thethickness of the EC layer 506 depends on the EC material selected forthe EC layer. The EC layer 506 may be about 50 nm to 2,000 nm thick.

An ion conducting layer 508 overlays EC layer 506. Any suitable materialmay be used for the ion conducting layer 508 provided it allows for thepassage of ions between the counter electrode layer 510 to the EC layer506 while substantially preventing the passage of electrons.

On top of ion conducting layer 508 is counter electrode layer 510. Thecounter electrode layer may include one or more of a number of differentmaterials that are capable of serving as reservoirs of ions when the ECdevice is in the bleached state. During an EC transition initiated by,for example, application of an appropriate electric potential, thecounter electrode layer transfers some or all of the ions it holds tothe EC layer, via the IC layer, changing the EC layer to the coloredstate. Concurrently, in the case of nickel tungsten oxide (NiWO), thecounter electrode layer colors with the loss of ions. Because counterelectrode layer 510 contains the ions used to produce the EC phenomenonin the EC material when the EC material is in the bleached state, thecounter electrode preferably has high transmittance and a neutral colorwhen it holds significant quantities of these ions. When charge isremoved from a counter electrode 510 made of NiWO (that is, ions aretransported from the counter electrode 510 to the EC layer 506), thecounter electrode layer will turn from a transparent state to a browncolored state. Thus when potential is applied to an electrochromicdevice, an optical transition occurs. Likewise, when an EC devicetransitions in the other direction, it behaves as a battery, andproduces an electrical charge by virtue of the ions traversing the IClayer in the opposite direction, current flows from the EC device.Multipurpose controllers described herein exploit this phenomenon bycapturing and/or diverting this charge to a power grid for reuse.

Although the foregoing invention has been described in some detail tofacilitate understanding, the described embodiments are to be consideredillustrative and not limiting. It will be apparent to one of ordinaryskill in the art that certain changes and modifications can be practicedwithin the scope of the appended claims.

We claim:
 1. A method of independently controlling tint states formultiple windows of a building, the method comprising: adjusting a firstwindow of the building to a first tint state selected from a pluralityof discrete tint states, wherein the first tint state is selected basedon a percentage of the first window covered by a shadow; adjusting asecond window of the building to a second tint state selected from theplurality of discrete tint states, wherein the second tint state isselected based on a percentage of the second window covered by theshadow, and determining the effects of the shadow on the first andsecond windows using one or more sensors, wherein the shadow hasdifferent effects on the first and second windows and the first tintstate is different from the second tint state, wherein the controllingof the tint states of the multiple windows is implemented by a systemcomprising one or more window controllers.
 2. The method of claim 1,wherein the shadow is a shadow of a cloud.
 3. The method of claim 1,wherein the shadow obscures the sun's rays differently on the firstwindow and the second window.
 4. The method of claim 1, wherein the tintlevels of the first and second window are different as a result of theshadow covering at least a portion of the first window and not coveringany of the second window.
 5. The method of claim 1, wherein the one ormore window controllers are connected with one or more networkcontrollers, which in turn are in communication with a mastercontroller.
 6. The method of claim 5, wherein the system furthercomprises a Building Management System.
 7. The method of claim 6,wherein the system communicates with the Building Management System viaa wireless communication.
 8. The method of claim 1, wherein the multiplewindows are electrochromic windows.
 9. A controller for controlling tintstates of multiple windows, the controller comprising: (a) acommunications interface configured to communicate with one or moresensors; and (b) controller logic configured to adjust a tint level of afirst window of a building to a first tint state selected from aplurality of discrete tint states, wherein the first tint state isselected based on a percentage of the first window covered by a shadow;and adjust a tint level of a second window of the building to a secondtint state selected from the plurality of discrete tint states, whereinthe second tint state is selected based on a percentage of the secondwindow covered by a shadow, wherein when the shadow has differenteffects on the first and second windows and the first tint state isdifferent from the second tint state.
 10. The controller of claim 9,wherein the communications interface comprises a wireless communicationsinterface.
 11. The controller of claim 9, further comprising a powersource for powering a reversible optical transition of at least one ofthe multiple windows.
 12. The controller of claim 11, wherein the powersource comprises a pulse width modulated amplifier.
 13. The controllerof claim 9, wherein the controller logic is further configured todetermine the effects of the shadow on the first and second windowsusing the one or more sensors.
 14. The controller of claim 9, whereinthe controller is part of a system comprising one or more windowcontrollers connected with one or more network controllers, which inturn are in communication with a master controller.
 15. The controllerof claim 14, wherein the system further comprises a Building ManagementSystem.
 16. The controller of claim 15, wherein the system is configuredto communicate with the Building Management System via a wirelesscommunication.
 17. The controller of claim 14, wherein the systemwherein the system comprises an HVAC system, a security system, aBuilding Management System, and/or a lighting system.
 18. The controllerof claim 9, wherein the multiple windows are electrochromic windows.